Starch is usually modified either chemically, physically or enzymatically to augment its convenience for industrial use. In the current study, starches from Enset and cassava plants were carboxymethylated, and factors which affect the carboxymethylation process and degree of substitution (DS) were studied. The application of the carboxymethyl starches as alternative pharmaceutical gelling agents for topical delivery of drugs was also investigated. Accordingly, nine different topical gel formulations of ibuprofen were prepared. All formulations were evaluated with respect to cosmetic qualities, pH, drug content, viscosity, spreadability, extrudability, in vitro drug release, anti-inflammatory activity and stability. The results showed that carboxymethylation was significantly affected by the starch source, reaction medium, temperature and time. All ibuprofen gel formulations showed homogeneous appearance, smooth texture and pleasant odor. The pH values of the formulations ranged from 6.80 to 7.22. Ibuprofen content ranged between 98.76 and 100.20% ensuring the uniformity of the drug content. The cumulative percent ibuprofen released over 12 h across cellulose membrane ranged from 43.8% cm -2 to 84.5% cm -2 . Spreadability, extrudability, the cumulative drug release and diffusion coefficient of ibuprofen were influenced not only by the rheological properties of the formulations but also by the nature of the modified starches. Physicochemically stable ibuprofen gels were obtained with potent anti-inflammatory activities.
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